Instructions to build GHC

[Harendra Kumar]

Hi,

I used to follow the instructions in INSTALL.md and README.md in the
root of the repo, and they always worked until recently. I am aware
that the make based system has been replaced by Hadrian. But it seems
these files are not updated with the new build instructions.

1. Either these files should be removed from the source or they should
be updated.
2. Where are the new build instructions? Is it hadrian/README.md? If
so can we put a pointer to that in INSTALL.md?

Thanks,
Harendra